Rename gitlab-api-client-go project key to client-go

What does this MR do and why?

Renames the projects.yml key gitlab-api-client-go to client-go, so the key matches the project's URL slug (gitlab-org/api/client-go). Also updates the three team member files that register the project under the old key.

Why: community MRs on gitlab-org/api/client-go currently get a review-request note that pings a random available MR coach instead of the project's own maintainers. The SuggestedReviewerService in contributors-gitlab-com derives the roulette key from the last URL path segment (client-go), but the project is registered under gitlab-api-client-go, so no maintainer matches. In the discussion on the original override MR (!2736, thread) we agreed to rename the key itself instead of adding a key-override mapping. @timofurrer confirmed there was no strong reason for the longer key.

Changes:

• data/projects.yml: rename the entry key
• data/team_members/person/f/fforster.yml, data/team_members/person/p/patrickrice.yml, data/team_members/person/t/timofurrer.yml: rename the key in each member's projects list

Companion MR (client-go Dangerfile): gitlab-org/api/client-go!3059 (merged)

Merge ordering

This MR and the companion Dangerfile MR should merge close together: while one side still says gitlab-api-client-go and the other says client-go, the client-go project's own Danger reviewer roulette silently stops matching its maintainers. Suggested order: this MR first, the Dangerfile MR immediately after. Once both merge, !2736 (merged) will be closed as unnecessary.

/cc @leetickett-gitlab